Copyrights © 2018 The Korean Society of Radiology 11

Case ReportpISSN 1738-2637 / eISSN 2288-2928J Korean Soc Radiol 2018;79(1):11-17https://doi.org/10.3348/jksr.2018.79.1.11

INTRODUCTION

The diagnosis of the spinal meningiomas is not very difficult based on radiologic findings and typical locations. However, diagnostic difficulties occur when the meningioma has atypical imaging characteristics or is in an unfamiliar location. Spinal meningiomas, which accounts for approximately 12% of all meningioma, are mostly intradural extramedullary in location (1). Some cases of intradural spinal meningiomas are associated with extradural extensions; however, it is uncommon to have pure epidural location. Extradural spinal meningiomas account for only 2.5% to 3.5% of all spinal meningioma (2). We report a case of pathologically confirmed spinal epidural meningioma. Additionally, we review the literature and the radiographic fea-tures of meningioma in unusual locations.

Case RepORT

A 58-year-old woman presented with progressive weakness and paraesthesia of both lower legs for four months. The wom-an showed paraparesis of motor Grade IV on both legs and had difficulty maintaining her balance due to weakness. She had hyperesthesia and dysesthesia on light touch, pain, and temper-ature sense below the T9 dermatome level. The position and vi-bration senses were intact. She did not have symptoms related to sphincter dysfunction.

A spine MRI demonstrated a well-defined mass approxi-mately 3.0 × 1.0 cm in diameter in the posterior epidural space of the seventh thoracic vertebral level on sagittal T1-weighted (Fig. 1A) and T2-weighted images (Fig. 1B). The mass caused compression and signal change of the spinal cord, suggesting compressive myelopathy. However, adjacent bone marrow was intact with no evidence of osseous infiltration. T1-weighted im-

Spinal Extradural Meningioma: A Case Report and Review of the Literature척수 경막외 뇌수막종: 증례 보고와 문헌고찰

Wonju Hong, MD1, Eun Soo Kim, MD1*, Yul Lee, MD1, Kwanseop Lee, MD1, Sung Hye Koh, MD1, Hwayoung Song, MD1, Mi Jung Kwon, MD2Departments of 1Radiology, 2Pathology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang, Korea

Spinal meningiomas account for 12% of all the meningiomas and are usually locat-ed in the intradural extramedullary space. In some cases, they are associated with some extradural extensions. However, purely extradural spinal meningiomas are rare. Additionally, it is difficult to make an accurate preoperative diagnosis. We re-port a case of pathologically confirmed atypical meningioma, presented as a poste-rior epidural mass on the thoracic spine. We review the case, clinical symptoms, ra-diologic findings and the histologic features.

Index termsSpineMeningiomaEpidural SpaceAdult

Received September 5, 2017Revised October 25, 2017Accepted December 23, 2017*Corresponding author: Eun Soo Kim, MDDepartment of Radiology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, 22 Gwanpyeong-ro 170beon-gil, Dongan-gu, Anyang 14068, Korea.Tel. 82-31-380-5985 Fax. 82-31-380-3878E-mail: silwater007@hallym.or.kr

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distri-bution, and reproduction in any medium, provided the original work is properly cited.

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Fig. 1. MRI and pathologic findings of spinal extradual meningioma in a 58-year-old woman who has progressive weakness of both lower legs for 4 months.A, B. The T1-weighted image (A) and the T2-weighted image (B) display the posterior epidural mass with a similar signal intensity to the spinal cord. The subarachnoid space is obliterated at the level of the mass and the spinal cord is compressed. The dura mater is seen as a dark line (ar-rows) separating the extradural mass from the intradural structures. Elevated signal change, within the compressed spinal cord, represents com-pressive myelopathy on the T2-weighted image (B). C, D. Contrast-enhanced sagittal (C) and axial (D) T1-weighted images depict strong and homogeneous contrast enhancement of the posterior epidural mass (arrows). Note the complete filling of the posterior epidural space and the extension to the left neural foramina of the vertebrae (D).

A

C

B

D

13

Wonju Hong, et al

jksronline.org 대한영상의학회지 2018;79(1):11-17

ages with contrast enhancement showed strong enhancement of the mass with a left neural foraminal extension of the T7 ver-tebrae (Fig. 1C, D). Preoperatively, the radiologic differential di-agnosis was lymphoma or metastatic tumor, but no primary le-sion was found in the quick preoperative radiologic evaluation.

The patient received excision with partial laminectomy of T7. Microscopic examination of the epidural space mass revealed an atypical meningioma. Histologically, the tumor was domi-nated by multiple vessels interspersed with small meningotheli-al tumor cells. Focal necrosis was also seen (Fig. 1E). The tumor cells showed increased mitoses up to 10 per 10 high-power fields despite bland cytological features (Fig. 1F). Tumor cells were also positive for epithelial membrane antigen (not shown). The final histological diagnosis was an atypical (WHO Grade II) meningioma.

After the surgery, the patient did not undergo further treat-ment such as post-operative radiotherapy. Nonetheless, the neu-rologic symptoms were relieved, and no evidence of tumor re-currence was shown on three month follow up CT.

DIsCUssION

Spinal meningiomas represent approximately 12% of all menin-gioma (1). Most meningiomas are intradural tumors that arise at the thoracic level. In the spine, meningiomas are thought to arise from the denticulate ligaments and more than 95% are clas-sified as WHO Grade I (3). Extradural component is thought to

be extended from an intradural mass. It is uncommon for a spi-nal meningioma to have an epidural location; in fact, exclusive-ly extradural spinal meningiomas are infrequent and account for only 2.5% to 3.5% of all spinal meningioma (2).

Spinal extradural meningiomas show the same histology, peak incidence in the fifth and sixth decades, the same frequent location in the thoracic spine and the same well-known sex pre-ponderance of female patients compared with intradural me-ningiomas (2).

The clinical findings of epidural meningiomas are not signifi-cantly different from those of intradural located ones. Patients may present with back pain, sensory and motor changes, and finally sphincter disturbances in late phases (2).

MRI is the best imaging modality to diagnose spinal meningi-omas. It delineates the location and extent of the tumor, guiding the plan of the surgery. However, extradural spinal meningio-mas are uncommon, and they can be mistaken as others. It affects the extent of the surgery and patient’s outcome, so the diagnosis of the extradural spinal mass needs to be carefully done.

Spinal meningiomas have typical features on MRI. On T1-weighted images, the mass often has signal intensity similar to that of the spinal cord and exhibits mildly increased signal in-tensity on T2-weighted images (1). In addition, the pattern of contrast enhancement is strong and homogeneous. Foraminal extension does not favor diagnosis of a meningioma over diag-nosis of a schwannoma or neurofibroma (1). The latter two le-sions usually demonstrate high signal intensity on T2-weighted

E FFig. 1. MRI and pathologic findings of spinal extradual meningioma in a 58-year-old woman who has progressive weakness of both lower legs for 4 months.E. Histologically, the tumor was dominated by multiple vessels (arrowheads) interspersed with small meningothelial tumor cells (arrows) and fo-cal necrosis (hematoxylin and eosin, × 100). F. Mitotic figures (arrows) are frequently identified, despite bland cytologic features of the tumor cells (hematoxylin and eosin, × 400).

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spinal extradural Meningioma

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Tabl

e 1.

Rev

iew

of t

he P

revi

ously

Rep

orte

d Ca

ses o

f Spi

nal E

xtra

dura

l Men

ingi

oma

Auth

orYe

arPa

tient

N

o.Ag

e/Se

xLo

catio

n(L

evel

)Cl

inic

al P

rese

ntat

ion

CT, M

RI F

indi

ngs

Path

olog

yTr

eatm

ent

Outc

ome

Suzu

ki

2002

158

/MT1

0–11

–12

Nor

mal

exa

m, A

bnor

mal

mas

s on

the

ches

t

radi

ogra

ph

Fibr

obla

stic

men

ingi

oma

T11–

12 h

emila

min

ecto

my

+

thor

acos

cope

Com

plet

e ex

cisio

n

Rest

repo

2006

157

/FC7

–T2

Loss

of s

tren

gth

in lo

wer

extr

emity

, incr

ease

in re

flex

MRI

: A h

omog

eneo

us e

nhan

cing

soft

tiss

ue

from

an

infil

trat

ive

proc

ess a

t C7–

T2 a

rea

invo

lvin

g th

e ep

idur

al sp

ace,

pred

omin

antly

on th

e rig

ht si

de, c

ompr

essin

g th

e co

rd

Psam

mom

atou

s

men

ingi

oma,

infil

trat

ions

Tota

l lam

inec

tom

y +

adju

vant

RT

No

recu

rren

ce

Fran

k et

al.

2008

(4)

145

/FC5

–C7

Chro

nic

post

erio

r

cerv

icot

hora

cic

pain

,

mild

bla

dder

dist

urba

nce

MRI

: An

enha

ncin

g ep

idur

al m

ass w

ith sp

inal

cord

disp

lace

men

t and

com

pres

sion

Psam

mom

atou

s

men

ingi

oma

C5–7

lam

inec

tom

y an

d

left

side

d fo

ram

inot

omie

s

with

C5–

T1

inst

rum

enta

tion

No

recu

rren

ce,

no sy

mpt

oms

Sant

iago

2009

142

/MT2

–T3

Para

pare

sisM

RI: P

oste

rior a

nd le

ft la

tera

l epi

dura

l mas

s

at T

2–T3

with

fora

min

al e

xten

sion

and

bone

rem

odel

ing.

Isoi

nten

se o

n T1

WI a

nd

T2W

I with

inte

nse

and

hom

ogen

eous

enha

ncem

ent

Psam

mom

atou

s

men

ingi

oma

T2–T

3 la

min

ecto

my

Com

plet

e ex

cisio

n

Kim

201

11

50/M

T6–T

7Pa

rest

hesia

at T

6M

RI: A

n in

tras

pina

l ext

radu

ral t

umor

loca

ted

from

the

T6 v

erte

bral

bod

y to

the

uppe

r

mar

gin

of th

e 7t

h ve

rteb

ral b

ody,

dum

bbel

l-

like

thro

ugh

the

inte

rver

tebr

al fo

ram

en

Men

ingo

thel

ial

men

ingi

oma

Hem

ilam

inec

tmoy

of T

6Re

cove

ry o

f the

sym

ptom

Tuli

2012

142

/FT5

–T6

Prog

ress

ive

low

er le

g

wea

knes

s and

num

bnes

s

belo

w T

3 fo

r 4 m

onth

s

MRI

: An

extr

adur

al le

sion

com

pres

sing

the

cord

from

T4

thro

ugh

T6, h

omog

eneo

us

enha

ncem

ent

WHO

Gra

de I

men

ingi

oma

T4–6

lam

inec

tom

yFu

ll re

cove

ry o

f mot

or

func

tion

Yald

iz 20

141

48/F

C7–T

2Hy

poes

thes

ia u

nder

T1

CT: A

mas

s orig

inat

ing

from

the

spin

al c

anal

and

exte

ndin

g to

the

hem

ithor

ax fr

om th

e

right

par

aver

tebr

al a

rea

at th

e le

vel o

f the

T1 v

erte

bra

and

exte

ndin

g to

war

d th

e T1

bony

spin

al c

anal

MRI

: Dum

bbel

l app

eara

nce

mas

s,

hype

rinte

nse

mas

s on

T2W

I, hy

poin

tens

e on

T1W

I with

hom

ogen

eous

enh

ance

men

t

Psam

mom

atou

s

men

ingi

oma

T1 to

tal l

amin

ecto

my

No

recu

rren

ce

15

Wonju Hong, et al

jksronline.org 대한영상의학회지 2018;79(1):11-17

Tabl

e 1.

Rev

iew

of t

he P

revi

ously

Rep

orte

d Ca

ses o

f Spi

nal E

xtra

dura

l Men

ingi

oma

(con

tinue

d)

Auth

orYe

arPa

tient

N

o.Ag

e/Se

xLo

catio

n(L

evel

)Cl

inic

al P

rese

ntat

ion

CT, M

RI F

indi

ngs

Path

olog

yTr

eatm

ent

Outc

ome

Jeon

g et

al.

2014

(5)

149

/FT1

2Lo

w b

ack

and

left

leg

pain

for 5

yea

rs,

hype

sthe

sia o

f the

left

leg

with

out m

otor

defi

cit

MRI

: A 1

.8cm

ext

radu

ral m

ass w

ith ri

m

enha

ncem

ent i

n th

e sp

inal

can

al

CT: E

xten

sion

to th

e m

idlin

e an

d th

e le

ft

T12–

L1 fo

ram

en, d

ense

cal

cific

atio

n w

ithin

the

mas

s

Psam

mom

atou

s

men

ingi

oma

T12

tota

l lam

inec

tom

y,

linea

r dur

otom

y at

the

mid

line

N/A

Yang

et a

l.

2016

(6)

155

/FT6

–T8

2-ye

ar p

rogr

essiv

e ba

ck p

ain

and

wea

knes

s in

both

legs

MRI

: A w

ell-c

ircum

scrib

ed o

val l

esio

n in

dors

al-la

tera

l spa

ce (I

soin

tens

e on

T1W

I,

hype

rinte

nse

on T

2WI,

hom

ogen

eous

enha

ncem

et w

ith d

ural

tail

sign)

Angi

omat

ous

men

ingi

omas

T6–8

lam

inec

tom

yM

otor

wea

knes

s

impr

oved

,

no re

curr

ence

Bett

asw

amy

et a

l.

2016

(7)

250

/MC2

–C4

Nec

k pa

in w

ith ti

nglin

g an

d

burn

ing

pare

sthe

sia o

f all

the

four

lim

bs fo

r 8 m

onth

s,

prog

ress

ive

spas

tic

quad

ripar

eiss

with

bla

dder

dist

urba

nce

for 1

wee

k

MRI

: An

extr

adur

al e

n pl

aque

lesio

n fr

om C

1

to C

4, tr

ansv

ersin

g th

roug

h th

e rig

ht C

2/3

inte

rver

tebr

al n

eura

l for

amen

, enc

asin

g

the

vert

ebra

l art

ery,

iso-t

o hy

poin

tens

e on

T1W

I, iso

inte

nse

on T

2WI w

ith in

tens

e

enha

ncem

ent

Men

ingo

thel

ial

men

ingi

oma

C2–4

lam

inec

tom

yCo

mpl

etel

y sy

mpt

om

free

, no

recu

rren

ce

41/M

C2–C

4Tin

glin

g se

nsat

ion

in th

e rig

ht

hand

with

pro

gres

sivel

y

incr

easin

g sp

astic

qudr

ipar

esis

for 4

mon

ths,

neck

mov

emen

t res

tric

tion

and

stra

in d

urin

g

mic

turit

ion

for 2

mon

ths

MRI

: An

extr

adur

al e

n pl

aque

lesio

n

exte

ndin

g fr

om C

3 to

C7

on th

e le

ft si

de,

hypo

inte

nse

on T

1WI a

nd T

2WI w

ith

inte

nse

enha

ncem

ent,

no tr

ansf

oram

inal

extn

esio

n or

wid

enin

g

Men

ingo

thel

ial

men

ingi

oma

Lam

inec

tom

ySi

gnifi

cant

alle

viat

ion

in sp

astic

ity a

nd

impr

ovem

ent i

n

mot

or p

ower

at 6

mon

ths f

ollo

w u

p,

no re

curr

ence

Khay

al e

t al.

2017

(8)

19/

FT5

–T7

Sudd

en p

rogr

essiv

e sp

astic

para

pare

sis o

f low

er li

mbs

with

bila

tera

l fee

t dro

p,

unab

le to

wal

k

MRI

: A 4

0 x

18m

m h

omog

enou

s enh

anci

ng

mas

s with

isoi

nten

se o

n T1

WI,

hype

rinte

nse

on T

2WI a

t ant

erio

r ext

radu

ral s

pace

on

left

side

caus

ing

com

pres

sion

and

disp

lace

men

t

of sp

inal

cor

d, w

ith p

oste

rior w

all v

erte

bral

body

ero

sion

and

dest

ruct

ion

of th

e

post

erio

r ele

men

t

Chor

oid

men

ingi

oma

T5–T

7 la

min

ecto

my

Reco

very

of m

uscu

lar

stre

ngth

to p

ower

Grad

e 3

N/A

= n

ot a

vaila

ble,

RT =

radi

othe

rapy

, T1W

I = T

1-w

eigh

ted

imag

es, T

2WI =

T2-

wei

ghte

d im

ages

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spinal extradural Meningioma

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images with cystic change and inhomogeneous enhancement (1). Therefore, the two tumors are easy to exclude. In addition, lymphoma, a malignant epidural mass, is the other misdiagno-sis of meningioma due to homogeneous and strong enhance-ment and low signal intensity on T2-weighted images due to its dense cellularity (2, 3, 5). Moreover, hyperostosis is observed less frequently in patients with epidural spinal meningiomas than in patients with cranial meningiomas (9). Hyperostosis was not clear in our case.

We have reviewed other 12 cases of spinal extradural meningi-omas previously reported since 2002 in Table 1. They were most commonly located in the thoracic spine followed by the cervi-cal spine, and patients showed predominance of female. On imaging studies, cases appeared as intraspinal extradural mass-es with mostly homogeneous enhancement. In most cases, the mass showed extradural en plaque lesion suggesting the dural based origin of the mass, also known as dural tail sign, making it dumbbell shape appearance. Nevertheless, our case did not present any signs that clarified that the mass originated from the dura. Compared to other reported cases, our case showed more well-delineated margin. These findings made it more dif-ficult to make the accurate diagnosis and it could easily be mis-taken as other extradural tumor such as lymphoma.

Pathologically, spinal meningiomas tend to be well-defined discrete lesions with a dural attachment. Microscopically, the common patterns are meningothelial, fibroblastic, transitional, and psammomatous and most case reports describe features of a miningothelial or psammomatous meningioma (2, 7). The WHO classification of meningiomas are divided into three grades. Among many subtypes, meningiothelial, fibrous and transition-al are the most common, and belong to Grade I. Our patient’s pathology report suggested atypical meningioma (WHO Grade II) with increased mitotic activity, focal necrosis and frequent vascular tumor emboli. Among reviewed 12 cases in Table 1, there is no case confirmed as atypical meningioma. Apart from one case of choroid meningioma (WHO Grade II) occurred in a 9-year-old girl, all of the other cases were Grade I meningiomas.

In literature review of major spinal meningioma series, in-cluding both intra- and extradural subtypes, recurrence rates of surgical excision are reported as 3% to 7% (2). Although, there

was no case which showed recurrence of the tumor among the reviewed 12 cases, the recurrence rate after surgery for extradu-ral meningioma is four times higher than that of intradural meningioma (4, 10). Our patient yet did not show any tumor recurrence for three months, but careful observation and follow up is still necessary.

In conclusion, we describe here a rare case of spinal extradural meningioma in the thoracic level with atypical one (WHO Grade II). However, it must be not forgotten that meningiomas may occur in rare locations and with variable imaging characteristics.

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척수 경막외 뇌수막종: 증례 보고와 문헌고찰

홍원주1 · 김은수1* · 이 열1 · 이관섭1 · 고성혜1 · 송화영1 · 권미정2

척수 수막종은 전체 수막종의 12% 정도를 차지하며 주로 경막내 수외 공간에 위치한다. 어떤 경우에는 경막 외로 연장되

기도 한다. 그러나 온전하게 경막외에 위치한 수막종은 드물며, 수술 전 정확한 진단을 내리기 어려운 경우가 있다. 우리

는 흉추의 후방 경막외 종양으로 나타난, 병리학적으로 확진된 비정형 수막종 증례를 보고하고 그 임상적 증상과 영상학

적 소견, 조직학적 특징에 대해 고찰하고자 한다.

한림대학교 의과대학 한림대학교성심병원 1영상의학과, 2병리과